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Two feeding experiments were conducted to evaluate the effect of readily available carbohydrate on performance of cattle and sheep fed low protein roughages and a liquid supplement. Exp. 1 consisted of two steer feeding trials to evaluate a basal diet (11.5% crude protein) consisting of 80% cottonseed hulls and 20% liquid supplement fed alone or supplemented with .454 kg per head daily of corn, wheat or roasted corn. The liquid supplement was a 32% crude protein supplement consisting primarily of cane molasses and urea. There were no differences (P>.05) among the cereal grain supplements in any of the performance, rumen or blood parameters studied. The basal diet promoted satisfactory growth and feed efficiency, and the results indicate that a low protein roughage, such as cottonseed hulls, may be fed successfully with a urea-based supplement. Exp. 2 consisted of two trials, each involving 30 individually fed lambs, to further evaluate the effect of various readily available carbohydrate sources on performance when low quality roughages were supplemented with a liquid supplement. Cornstarch, dextrose and roasted corn were fed at 5% of the diet with cottonseed hulls and liquid supplement or weathered fescue hay and liquid supplement in a 3 × 2 factorial arrangement of treatments. Similar performance, rumen volatile fatty acids (VFA) and blood urea nitrogen (BUN) values were observed for the various carbohydrate sources and there were no interactions (P>.05) observed between carbohydrate source and roughage source. Lamb fed cottonseed hull diets gained faster (P<.01), consumed more daily feed (P<.01) and had more favorable feed to gain ratios than those fed fescue hay diets.

Three trials were conducted to study the effects of elevated dietary iodine intake on the performance, thyroid gland development, certain blood constituents and other measures in calves. Each trial consisted of 32 individually fed Holstein bull calves fed four levels of iodine. Iodine, as calcium iodate, was added to a basal diet at the rate of 0, 10, 100 and 200 ppm; 0, 25, 50 and 100 ppm; and 0,10, 25 and 50 ppm for Trials 1 through 3, respectively.Elevated dietary iodine depressed gain and feed intake, the magnitude being significant for diets containing 50, 100 or 200 ppm added iodine in at least one trial. The feeding of either the 100 or 200 ppm diets, and in some cases lower levels, produced symptoms of toxicity including coughing and profuse nasal discharge. In Trial 1, the addition of 200 ppm iodine tended to produce heavier thyroid glands, on a body weight basis, and in Trial 2 this occurred at all levels. In Trial 3 there was a tendency toward lighter thyroids in calves fed all levels of added iodine. Calves receiving added iodine also tended to have heavier adrenal glands at the conclusion of Trials 2 and 3. All calves fed supplemental iodine had markedly higher concentrations of serum iodine throughout the trials, and those fed the 200 ppm diet had significantly lower blood hemoglobin and serum calcium and tended to have higher serum BEI levels at the end of Trial 1. Considering all trials, no consistent differences in rumen volatile fatty acid patterns were observed.It appears that the minimum toxic iodine level for calves is near 50 ppm although a portion of the animals were adversely affected at lower levels. Differences in adrenal weights and trends in growth rate indicate that levels as low as 25 ppm were undesirable. Sub-toxic levels (as measured by performance) tend to increase serum iodine and may or may not result in slightly enlarged thyroids and a transient period during which the animals exhibit signs of iodinism.

Fifty-six Holstein male calves were used in two experiments to determine the minimum toxic level of iron and the effect of high levels of dietary iron on performance and blood constituents. A ration compounded from natural feedstuffs and containing 100 ppm iron was used as the basal in both experiments. Ferric citrate was added to the basal ration to give the desired iron levels. In Experiment I the levels of iron were 100, 500, 1,000 and 2,000 ppm. Six individually fed calves received each of the four rations during a 70-day experimental period. Blood hemoglobin and serum iron were significantly increased at the high dietary levels of iron. Serum inorganic phosphorus was significantly depressed as dietary iron increased. No significant difference was found between treatments in weight gain, feed intake and feed conversion or in serum calcium, magnesium, alkaline phosphatase activity, copper and zinc. In Experiment II, the levels of iron were 100, 1,000, 2,500 and 4,000 ppm. Eight calves were individually fed each of the four rations for 98 days. No significant difference was found in serum calcium, magnesium, copper, or zinc. Significant depressions in weight gain, feed intake, and serum inorganic phosphorus were noted with increasing dietary iron. Feed necessary per pound of gain, blood hemoglobin, and serum iron were found to be increased with increasing dietary iron. The maximum level of dietary iron which the calf may consume without marked depression in feed intake and body weight gain appears to be approximately 2,000 ppm.

Two experiments utilizing 104 Hereford steers were conducted to study the influence of low levels of roughages and roughage substitutes on performance, carcass characteristics, rumen environment, rumen parakeratosis and liver abscesses of steers fed high energy rations. The treatments were: basal all-concentrate ration; basal plus 1.36 kg. hay per head daily; basal containing 5% cottonseed hulls; or 5% ground corn cobs; or 2% oyster shells, or 4% oyster shells; or 2% sand; or 5% ground polyethylene. Eighty steers were group fed in Experiment I and 24 steers were individually fed in Experiment II.The addition of low levels of roughages and roughage substitutes to the basal ration did not significantly increase body weight gains in Experiment I. In Experiment II, the addition of cottonseed hulls to the basal ration significantly increased gains (P<.05) over the basal and basal plus 2% or 4% oyster shell rations. Steers on the basal, basal plus hay and basal plus cob treatments yielded carcasses with larger ribeyes, thinner rinds and improved cutability scores, while carcass grades and marbling scores were not significantly different from the other treatments.The basal plus hay was the only treatment which gave any appreciable protection against rumen parakeratosis and liver abscesses. Total volatile fatty acids was highest and pH lowest on the basal and basal plus 2% oyster shell treatments in Experiment I.These two treatments also elicited severe rumen parakeratosis and a high incidence of liver abscesses. Rumen pH was highest on the basal plus hay treatment in both experiments. Lactic acid concentrations and molar percentages of VFA's could not be related to incidence of rumen parakeratosis and liver lesions in these experiments.

Thiouracil intakes of 0.175 gm. to 0.544 gm. per lamb per day had no significant effect on the rate of growth as measured by total gain in weight, although rate of gain was slightly reduced in all lots receiving thiouracil.Thiourea produced significant reductions in lamb growth when fed at levels ranging from 0.048 to 0.071 gm. per lamb daily.Feed intake was somewhat reduced in all the groups receiving thiouracil and thiourea. Neither thiouracil nor thiourea was relished by lambs and both were definitely unpalatable.The feed requirements per pound of gain were not affected by thiouracil until intake exceeded 0.353 gm. daily but there was a tendency for the gross efficiency to be reduced as the levels of thiouracil and thiourea were increased.Thiouracil and thiourea at all levels fed produced highly significant increases in thyroid weight.The largest numbers of top grade (AA) carcasses occurred in the lots receiving 0.175 and 0.333 gm. of thiouracil per lamb daily. These lot differences approached statistical significance.

There remains little doubt that beef cattle may be finished successfully on all-concentrate rations. Bodyweight gains comparable to those on conventional rations can be obtained. It logically follows that dressing percentage will be somewhat improved due to lack of “wastiness” in cattle receiving rations which are not bulky. Finished weights are reduced about 20 kg. by this system of feeding. Compared to cattle on more conventional feeding systems, the quantity of feed necessary per unit of gain is decreased by the use of high energy feeds and the attendant feed mixing and handling is reduced accordingly. The system also lends itself to mechanical handling of feed as well as taking advantage of the highly mechanized production of grains and the present low cost of nutrients from grains compared to roughages when these items must be purchased and transported.On the other hand, it must be recognized that we do not really know why the animal fed an all-concentrate ration will limit its feed intake to an energy level comparable to that on a conventional ration or what can be done to increase consumption to take advantage of the “extra space” in the rumen resulting from the removal of roughage.It seems logical and important to keep feed before the animals at all times with facilities that are conducive to frequent eating to minimize problems of bloat and founder. Best methods of getting animals on full feed and keeping them eating at optimum levels have not been fully investigated; however, a gradual change from a high roughage ration appears preferable to an abrupt change.The last word has not been said regarding the use of buffers. Trace mineral and vitamin fortification as influenced by removal of roughage needs further investigation. Although liver abscesses may be prevented by low-level continuous feeding of a broad spectrum antibiotic, no product other than roughage has yet been discovered which will prevent rumen parakeratosis. Depending on the nature of the roughage it appears that about 10 to 15% is necessary to maintain a healthy rumen epithelium. More attention to feeding and management details is necessary with allconcentrate feeding programs and should be attempted only by those producers who are able and willing to give this attention.In conclusion, it appears that all-concentrate feeding has many features which are attractive to cattle feeders but there are still many attendant problemsto be solved. Given time and research effort these problems will no doubt be solved and all-concentrate feeding of beef cattle will take its place along with other cattle feeding systems with economic factors determining the extent of its use.

Two experiments involving four trials were conducted over a 2-year period to determine the influence of added roughages in various physical forms and chlortetracycline on performance, rumen characteristics and liver abscesses of steers fed a ration based largely on ground shelled corn. A 2×4 factorial arrangement of treatments was used to compare the basal all-concentrate ration with rations containing limited roughage (ground rice hulls, whole rice hulls, and long hay) fed with and without chlortetracycline. Feedlot performance and carcass data were not significantly influenced by roughage or antibiotic treatment.Steers fed long hay had a significantly higher percent of rumen acetic acid with a correspondingly lower percent of propionic acid than steers fed other feeding treatments. Adding fiber in the form of ground rice hulls and hay resulted in significantly (P<.05) higher percentages of butyric acid (Experiment I) when compared to the basal ration. Altering the physical form of the rice hulls or antibiotic treatment had no consistent effect on rumen VFAs. Rumen fluid of steers fed hay had considerable higher pH values than steers fed no hay. Ruminal pH of steers fed either the basal or rice hull rations was similar.Severe rumen parakeratosis was observed in steers fed no roughage or ground roughage. Coarse roughage in limited amounts (either 5% whole rice hulls or 1.36 kg. long hay) significantly improved health of the rumen epithelium. Steers fed the basal or basal plus ground rice hulls exhibited severe clumping and sloughing of papillae with considerable hair accumulation in the rumen mucosa. Chlortetracycline appeared to be ineffective in improving health of the rumen epithelium.Twenty-three of 128 steers involved in this study had abscessed livers. Sixteen of the 23 were found in steers fed the basal or ground rice hull rations. Five of the abscessed livers were found in steers fed whole rice hulls and two in steers fed hay. A marked reduction in abscessed livers was achieved by the inclusion of 75 to 85 mg. of chlortetracycline per head daily (33 vs.3%).

Sixty-four Holstein male calves were used in two experiments to study the effect of nitrite and hydroxylamine on the performance and vitamin A and carotene metabolism of ruminants.The results of the combined analysis of Experiments I and II indicated that the levels of hydroxylamine (2.2 gm. and 4.4 gm./100 kg. body weight) fed in the experiments lowered feed intake and weight gain. The feeding of potassium nitrite had no effect on performance. The 4.4 gm. level of hydroxylamine also resulted in lower hemoglobin and higher methemoglobin levels. Neither level of hydroxylamine or potassium nitrite had any effect on the vitamin A status of the calves as measured by serum vitamin A, serum carotene and liver vitamin A levels. There was no indication of an interaction between nitrate reduction products and vitamin A.Experiments III and IV were conducted to determine if nitrate or nitrate reduction products accelerate the destruction of vitamin A or carotene when incubated with rumen fluid in vitro. Vitamin A and carotene destruction was no more rapid in the incubation flasks containing rumen fluid from nitrate and nitrite-fed steers (17.6 gm. and 4.4 gm. per kg. bodyweight, respectively) than in those containing fluid from control steers. The addition of hydroxylamine to incubation flasks did not significantly accelerate vitamin A or carotene destruction.The results of these investigations indicate that the nitrate reduction products, NH2OH and KNO2do not interfere with vitamin A and carotene metabolism of ruminants.

Two experiments involving 104 steers were conducted to study the influence of nitrogen source and added sulfur in finishing rations comparing two levels of sulfur and soybean meal, urea, Starea and urea+alfalfa meal supplements in Experiment I and urea with Starea supplements in Experiment II. Results revealed that feedlot performance, carcass data and ruminal fluid constituents were unaffected by nitrogen source. Consumption of rations with added sulfur was lower in both studies and utilization of feed was more efficient by steers fed high sulfur rations in Experiment I. Feedlot gain, carcass gain and carcass weight were significantly decreased in steers fed high sulfur rations (Experiment II). Lower molar percentages of acetate and greater molar percentages of propionate and valerate were detected in rumen fluid from steers receiving supplemental sulfur in Experiment I. Acetate to propionate ratios were also significantly lower in cattle fed high sulfur rations.Similar treatments involving sources of supplemental nitrogen and the addition of sulfur as in Experiment I were imposed on 100 calves which were fed a growing ration based on corn silage. Calves supplemented with SBM had greater average daily gains than calves fed urea, urea+alfalfa meal or ground corn supplements. The response of calves fed Starea was intermediate between that of calves fed SBM and those fed other urea-containing supplements. The addition of elemental sulfur did not influence performance.Levels of ammonia were markedly higher in samples from a fistulated steer receiving urea than from one receiving SBM. An early rise followed by a rapid decline of ruminal ammonia was detected in rumen contents from the steer fed Starea.

Twenty hogs were divided into five groups of equal numbers of which four groups were fed a soft fat producing basal diet containing 10% soybean oil. Three groups were fed to varying specified weights at which time coconut oil, a hardening oil, replaced the soybean oil until the hogs reached slaughter weight. The fourth group received soybean oil from weaning weight to market weight, while the fifth group received coconut oil for the same period. When the hogs were fed coconut oil from weights of 150 to 205 lb. during the last 30 days of the fattening period, carcasses were satisfactory in firmness.Determinations made on the fat showed decreases in iodine number as the length of feeding period on coconut oil increased. Decreases were similarly found for linoleic, linolenic and arachidonic acids. Fat stability tests conducted by determining periodically the peroxide values on stored cured bacons of each carcass supported the fatty acid composition values and manual firmness scores.

THE effectiveness of thiouracil and related compounds in inhibiting the action of the thyroid gland has been established in the human and in many other species. The possible use of these compounds to alter the growth rate, fattening efficiency and market quality of animals because of thyroid alteration has been investigated with several species. Much of the early work with these materials was done with the rat. The administration of thiouracil to growing rats has been shown to retard growth by numerous workers: Hughes 1944; Gordon, Goldsmith and Charipper (1946), and Williams, Weinglass, Bissell and Peters (1944).Astwood, Bissell and Hughes (I944) reported that 0.5 percent thiouracil in the ration of young chicks greatly retarded growth and development although o.I percent thiouracil in the ration did not impair growth. Kempster and Turner (1945) reported that thiouracil fed to ten week old New Hampshire broilers for a 16 day period did not retard growth.

Sixty steers were fed six different rations composed of varying amounts of grain and grass. A sample from each carcass was analyzed for moisture, fat, myoglobin, total pigment, color reflectance of lean and yellow pigment in the fat. Significant differences were found between certain treatments for all measurements involving color of lean and fat. The differences in color of lean were due to varying amounts of fat and moisture rather than to a difference in the quantity of pigments present. With respect to color all samples aged equally well during a 7-day storage period at 35° F. The brightest colored samples prior to storage, however, were also the brightest after storage.

Early-weaned pigs were fed liquid diets containing fully-cooked soy flour as the only source of protein. Other ingredients were fat, lactose, methionine, minerals, vitamins and an antibiotic. The results indicate that the nutritive value of soy flour for early-weaned pigs was markedly improved by exposing the flour to an alkaline environment, pH 10.6, prior to its inclusion in the diet. Pigs fed alkali-treated soy flour grew significantly faster and more efficiently than pigs receiving the untreated soy flour. A 30-min. alkali treatment was as effective as a 5-hr, treatment. The nutritional value of finely-ground soybean meal was also improved by treatment with alkali. These studies failed to reveal the nature of the alteration induced in soy flour by the alkali treatment or the manner in which this change enhances the utilization of nutrients by the pig. Reducing the buffering capacity of the soy flour with acid did not improve growth performance. Similarly, supplementation with methionine, threonine and lysine, either singly or in combination, failed to improve pig gains. Analysis of alkali-treated and untreated soy flours failed to reveal any marked change in amino acid content.

MANY researchers make use of the possibility of alloting animals to treatments in accordance with some predictor of performance of these animals in the experiment (Henderson, 1959). Attempts have been made to find indicators or predictors of carcass traits in the live animal (Orme et al., 1960; Rollins et al., 1962). Allotment to experimental treatments based on predicted performance resulted in only slight improvement over allotment based solely on body weight. Growth rate and efficiency of feed utilization are reported to be moderately heritable and highly correlated (Lickley et al., 1960; Koch et al., 1963; Swiger et al., 1965). Heritability estimates for feed consumption have been reported as high as 98% (Swiger et al., 1962). This study was undertaken to investigate the value of voluntary energy intake as a predictor of feedlot performance and certain carcass characteristics in beef cattle.Experimental ProcedureThe performance data employed were obtained from 280 beef steers in 10 feeding trials in which predominately all-concentrate rations were individually fed. (Wise et al., 1961; Wise, Blumer and Barrick, 1963; Wise et al., 1965a, b; Harvey et al., 1968; Wise, Haskins and Barrick, 1967; Haskins, Wise and Barrick, 1967; Wise, Barrick and Haskins, 1969).

Four trials, involving a total of 144 pigs, were conducted to determine the effects of varying the ratio of amino acids from corn and soybean meal, and the dietary protein level on performance, carcass quality and diet digestibility. The diets contained a 60:40, 50:50 or 40:60 ratio of amino acids from corn and soybean meal. The pigs were self fed from an initial weight of 20.9 kg. to approximately 95 kilograms.The results of this study indicate that satisfactory growth can be obtained from weanling (21 kg.) pigs fed a 11.3% protein corn-soybean meal diet when at least 50% of the amino acids is supplied by soybean meal. At least 12.8% protein with 50% or more supplied by soybean meal was required for maximum feed efficiency, and carcass leanness was improved up to 14.3% dietary protein. A further increase in dietary protein level did not result in a further increase in lean cuts. The level of amino acids required appears to be different for maximum growth, feed efficiency and muscle development.

Eighty steers were used to study the effects of urea versus soybean meal, 11% protein vs.14% protein and Bacitracin supplementation on performance, carcass characteristics, rumen environment and liver abscesses of cattle fed all-concentrate rations based on ground shelled corn. Increasing the level of protein from 11% to 14% significantly increased gains. An apparent but nonsignificant increase in growth response was obtained from Bacitracin supplementation. Performance of steers fed rations containing urea was comparable to steers fed soybean meal.A significantly greater percent of butyric acid was observed in rumen fluid of steers consuming rations containing 14% protein. Differences in pH and buffering capacity of rumen fluid could not be related to levels of protein, sources of protein or Bacitracin supplementation. Significant interactions between protein treatments and Bacitracin treatments for pH and buffering capacity were observed.Rumen parakeratosis was present in all steers at slaughter. Dark-colored papillae as well as extensive sloughing and clumping were found in a large proportion of rumen wall samples. Seventy-two percent of the livers were condemned at slaughter due to liver abscesses. Degree of severity of rumen parakeratosis and incidence of liver abscesses could not be related to levels or sources of protein, or to presence of Bacitracin in the rations.

One hundred and forty-eight first-litter gilts and 40 second-litter sows were used in four trials to study the influence of two levels of energy and two levels of protein intake during gestation on gain and reproductive performance. The treatments were 3 or 6 lb. of feed daily, containing either 0.3 or 1.2 lb. of protein. Energy was supplied by corn starch, sugar and fat and protein was supplied by soybean meal (50% protein). Vitamins and minerals were fed to provide an equivalent daily intake for all treatments. All gilts were placed on experiment individually at the time of breeding and were fed in confinement.Gilts fed the high energy level gained significantly more weight during gestation than those fed the low energy level. The low energy level fed during gestation appeared to be adequate for reproduction and apparently did not greatly hinder lactation performance as measured by litter weight at weaning.In trial 1, gilts fed the low energy level farrowed significantly more live pigs while, in trial 2, gilts fed the high energy level farrowed more pigs and the litters were significantly heavier at birth. In trials 3 and 4 there was no significant difference in live pigs farrowed between feeding levels. In each of the four trials, heavier pigs were farrowed by gilts receiving the higher energy intake. Level of energy intake during gestation did not significantly influence pig survival, number of pigs weaned or litter weight at weaning. Level of protein did not significantly affect reproductive performance as measured by number of pigs farrowed, birth weight, pig survival, or litter weight at weaning.

The livers from pigs fed diets containing one of eight different cottonseed meals of known processing history were analyzed for free and bound gossypol and iron. Gossypol content of the livers was found to be directly related; and iron content, inversely related to total gossypol content of the diet.A total of 136 weanling rats were used in two experiments to study the influence of dietary protein level on the toxicity of injected gossypol. In the second experiment dietary iron, injectable iron, dietary lysine and the combination of dietary iron and lysine were studied in relation to the toxicity of injected gossypol.Dietary protein level did not alter the toxicity of injected gossypol. Likewise, the other dietary treatments were without beneficial effect. Iron-dextran injected into the peritoneal cavity simultaneously with corn oil containing gossypol was partially effective in preventing the growth depression resulting from injected gossypol but was not completely effective in overcoming the death losses which resulted.

Seventy-two pigs were used to determine the influence of calorie-protein ratio and fat level in the ration on performance and carcass characteristics. The rations, containing graded levels of from 10 to 18% protein, were formulated so that a similar ratio of amino acids was maintained in all diets. Daily feed consumption was influenced by both calorie-protein ratio and by fat level in the ration. However, gross energy intake was not significantly influenced by either ration treatment. Growth rate, during the first 28 days on test, was significantly influenced by energy-protein ratio. The narrow ratio supported the most rapid rate of gain. This difference was not apparent at the time the pigs reached market weight. Added fat resulted in a significant improvement in both rate of gain and in feed per pound of gain. Energy utilization, however, was not influenced by either calorie-protein ratio or by fat level in the ration. Physical measurements and chemical determination made on the carcasses were not significantly influenced by ration treatments. Factors influencing feed consumption of pigs are discussed.

Eighteen steers in drylot were fed rations containing 0, 2.5, or 5.0% added animal fat. Samples of rib fat from each steer were analyzed for fatty acid composition by means of gas chromatography; similar determinations were made on fatty acids in the ether extractable portions of the rations. Measurements were also made in respect to a number of carcass characteristics. The addition of animal fat to the steer rations resulted in a significant increase in percentage of separable rib fat in those animals previously receiving a low-energy ration, but not in steers wintered on a higher-energy ration; a similar situation existed in respect to thickness of rind. The addition of animal fat to the rations resulted in a highly significant increase in stearic acid content of rib fat.Samples of rib fat from 20 pasture steers were also analyzed for fatty acid content. The deposition of myristic acid was significantly greater in steers receiving a grain ration with 10% added fat. The depression of the percent of oleic acid deposited in steers receiving implants of diethylstilbestrol was highly significant. It appears that the hormone depressed the deposition of palmitic acid in steers receiving added dietary fat, and stimulated such deposition in steers on a grain ration containing 7–10% salt; the condition was reversed in respect to palmitoleic acid deposition. The percent of palmitoleic acid was quite high in all samples of rib fat from pasture fed steers as compared to that from steers fed in drylot.

The results of an investigation to determine the effect of protein source on toxicity of gossypol in swine rations are presented. Peanut and soybean meal were used as the sources of supplemental protein in Experiment I and cottonseed and soybean meal in Experiment II. Cottonseed meats were added to the rations containing each source of protein to obtain graded levels of free gossypol. Six pigs were individually fed each ration.The toxicity of free gossypol, as measured by feed intake, gain and mortality of swine was influenced by both the source of protein and the level of free gossypol. There was a significant (P<0.05) protein-source × level-of-free-gossypol interaction associated with feed consumption and daily gain. Soybean meal rations gave superior performance to peanut or cottonseed meal rations at all levels of free gossypol.Efficiency of feed utilization was not significantly affected by gossypol addition to the ration. The mortality rate was lower for pigs fed soybean meal rations than for pigs fed peanut or cottonseed meal rations.

Thirty-four Hereford calves were used in two experiments to determine the feasibility of feeding all-concentrate rations to beef cattle. In the first experiment which was a growth-performance study, a basal diet containing 1.5% fiber and composed of ground shelled corn, urea, cottonseed oil, minerals and vitamins was compared to a similar diet with sodium and potassium bicarbonate added at a level of 11% of the total ration. This level of cation supplementation proved to be excessive; however, performance on the basal diet (1.89 lb. daily) stimulated a second experiment. In this study which included carcass evaluation as well as growth-performance, the basal diet was supplemented with either 5% sodium and potassium acetate or 2.5 lb. per day of ground or long hay. Performance of calves on the unsupplemented basal ration equaled that of calves fed any of the other three diets. Feed conversion on the basal ration alone was slightly superior to conversion on diets containing acetate salts or hay in either form. The presence of acetate salts in the diet adversely affected growth-performance and produced carcasses with less finish than the other three diets. On the basis of these data, it was concluded that calves are able to perform satisfactorily on all-concentrate rations for extended periods of time if the ration provides essential nutrients in adequate amounts and the buffering capacity of the rumen is adequate. The possible rumen buffering capacity of ammonium ions from urea is discussed. Types and levels of buffering agents in all-concentrate rations for ruminants merit further study.

Graded levels of free gossypol from cottonseed meats were added to corn-degossypolized cottonseed meal and corn-soybean meal diets for growing pigs. Solubility of the soybean nitrogen was reduced from 85% to 35% by autoclaving for 2 hours at 17 lb. of steam pressure. Solubility of cottonseed nitrogen was reduced from 87.4% to 79% by autoclaving for 30 minutes. Rate of gain of pigs fed the autoclaved meals was not significantly reduced. Addition of free gossypol at the levels of 0.03% and 0.036%, respectively, to both corn-cottonseed meal and corn-soybean meal diets resulted in depressed growth and death of the pigs.In a second study autoclaving degossypolized cottonseed meal for 3 hours at 17 lb. of pressure reduced growth of pigs from 1.26 lb. to 0.38 lb. per day. Addition of 0.2% of L-lysine resulted in growth almost equal to that of pigs receiving non-autoclaved meal (1.09 lb. per day). This was in the presence of 0.026% of added free gossypol. When the free gossypol level was increased to 0.036% of the diet, growth rate was reduced and four of six pigs died from gossypol toxicity. There was no evidence that addition of 0.2% of L-lysine to this high gossypol ration improved growth or reduced death losses.

Two experiments were conducted to compare xylose and glucose as sources of carbohydrate in the diets of young pigs.Experiment I consisted of a growth-performance study using 4 replications of pigs, which were hand fed three purified diets containing 37.4% of sugar, glucose, xylose, or a 50-50 mixture of the two. Experiment II included studies of nitrogen retention and sugar recovery as well as of growth-performance; data were obtained from 5 pairs of pigs, which were pair-fed comparative diets containing 56%, resspectively, of glucose or of xylose.Growth-performance and balance studies indicated that pigs were able to utilize glucose to a greater degree than xylose.Cataract formation resulted after feeding a diet containing xylose at the level of 56% of the dry matter.Voluntary activity was decreased, and the color of the hair coat was altered from deep red to yellowish-red in pigs fed xylose.

Fifty-two Holstein male calves were used in two experiments to determine the minimum dietary toxic level of manganese and the effect of high levels of dietary manganese on performance and blood constituents. A basal ration containing 12 ppm of manganese was used in both experiments with manganese sulfate added to give the desired manganese levels. In Experiment I levels of added manganese were 0, 820, 2460 and 4920 ppm with seven individually-fed calves per treatment. Body weights were taken and blood was sampled at 14-day intervals throughout the 84-day experimental period. Body weight gains and feed intake were depressed at the high dietary levels of manganese. No significant differences were found between treatments in feed efficiency, hemoglobin, serum calcium, serum inorganic phosphorus, serum magnesium or serum alkaline phosphatase activity. In Experiment II levels of added manganese were 0, 1000, 2000 and 3000 ppm with six calves per treatment fed for 100 days. The four calves comprising each replication received equal amounts of feed. No significant difference was found in average daily gain or feed efficiency. A significant depression in blood hemoglobin level was noted with increasing dietary manganese. No differences were found between treatments in any of the serum constituents measured. A brief study was conducted in which graded levels of manganese were added to incubation flasks containing washed cell suspensions of micro-organisms from fistulated cows fed no manganese or 5000 ppm of dietary manganese. Depressed volatile fatty acid production, especially propionate, and marked changes in the rumen flora were observed at high levels of dietary manganese.

A total of 120 animals were used in four experiments to study the influence of rumen buffering agents or hay fed at different levels on performance and carcass characteristics of beef cattle fed an all-concentrate ration based on ground shelled corn. Compared to soybean meal as a supplemental protein source, urea resulted in a slight decrease in feed intake but very little change in performance. Addition of sodium bicarbonate or sodium and potassium bicarbonate to the SBM basal slightly increased feed intake and rate of gain; however, the increases were not significant. Additional calcium carbonate (limestone) resulted in slightly increased feed intake and performance when mixed thoroughly with the ration in the individual feeding studies, but caused a decreased intake and gain when spread over the top of the basal ration at feeding time and stirred into the feed in the group feeding studies. Long hay in limited amounts (3 lb./head daily) or fed ad libitumdid not significantly influence performance or carcass characteristics when added to the all-concentrate basal ration. Studies are presently being conducted on the relationship of high energy rations to rumen and liver lesions.

Ten percent protein rations were formulated to supply 12.5, 25, and 50% of the protein from dehulled S.B.M. The remainder of the protein was supplied by corn. These rations were fed with and without 0.4% of added lysine during two consecutive seasons. Six pigs were individually fed each ration during each season.Increasing the proportion of the protein supplied by S.B.M. resulted in significant increases in feed intake and daily gain. Carcass leanness as measured by area of longissimus dorsimuscle was significantly improved by increasing the percent of protein supplied by S.B.M. and by added lysine.

The discovery of thiouracil and its derivatives as potent substances for inhibiting the function of the thyroid gland (Astwood, 1943; Astwood et al., I945 and McGinty and Bywater, I945) has made it possible to study some of the effects of limiting thyroid functions. A detailed report indicative of the effects of these substances on the thyroid gland is given by Astwood et al. (1943). They reported rapid enlargement of the thyroid glands of rats during the first few weeks of treatment. Microscopic examination showed a marked hyperplasia of the follicular epithelium, a decrease in stored colloid and an increase in vascularity of the glands. The thyroid glands of rats treated for two to six months with a diet containing 2 percent sulfagaanidine or 0.1 percent thiourea in the drinking water still exhibited an orderly cellular arrangement and upon cessation of treatment the glands rapidly regressed toward a normal condition.

The construction of a metabolism unit of simple design and operation is described which provides for the quantative separation and collection of feces and urine eliminated by steers and heifers. The unit including metabolism stall, equipment construction and operation is illustrated by labelled diagrams and photographs.

TWO 98-day experiments were conducted to determine the effect of added dietary levels of copper sulfate and an antibiotic on performance, blood constituents and liver copper levels of young growing calves. In both experiments four levels of copper and two levels of chlortetracycline were compared in a 2 × 4 factorial arrangement. Added dietary copper levels of 0, 125, 250 and 500 ppm were fed in Experiment I and 0, 300, 600 and 900 ppm in Experiment II. Each of the copper levels was fed with and without 22 mg chlortetracycline/kg feed.Results of Experiment I and II indicated a significant (P<.05) increase in average daily gain due to chlortetracycline. Copper increased average daily gain significantly (P<.05) only in Experiment II. Also present in Experiment II was a significant (P<.05) interaction between chlortetracycline and copper in that copper levels gave no additional response over that observed from chlortetracycline. Carcass gain and percent shrink showed a significant (P<.05) increase due to added copper in Experiment II but not in Experiment I. In both experiments liver copper levels indicated a highly significant (P<.01) increase due to copper levels fed. Serum calcium levels in Experiment II were significantly (P<.05) decreased in calves receiving chlortetracycline. Other blood constituents in both experiments indicated no changes due to treatments. Rumen VFA analyses obtained at the end of Experiment II showed no response to treatments.